Chapter 15 Lipids

1. Chapter 15Lipids • SWBAT: • Describe a lipid • Describe the classes of lipids

2. What are lipids? Group of molecules not defined by structure but by common characteristics • They are: • non-polar • soluble in non-polar solvents like methylene chloride, gasoline, ether • not soluble in polar solvent like water • fats, oils, fatty acids, waxes, steroids, cholesterol, fat soluble vitamins

3. Lipids and Health • BMI: Body Mass Index: Body Fat vs Obesity • Blood Lipids

4. CAD:Coronary Artery Disease • Lipid deposits clogging arteries in the body and heart • Risk Factors for CAD • Hypertension, Diabetes, elevated cholesterol • smoking • sedentary lifestyle • stress • obesity • male sex • family history • older age

5. Types of Lipids Saponifiable Lipids: Prostaglandins Waxes Tricylglycerols Glycerophospholipids Non-Saponifiable Lipids: Cholesterol Steroid hormones Can be Hydrolyzed Can NOT be Hydrolyzed

6. Homework Chapter 15.1 Pg 497 #15.2 – 15.4 (even)

7. SWBAT: Write structures of fatty acids ID saturated and unsaturated fatty acids Chapter 15Fatty Acids

8. Fatty Acids Contains a long carbon chain attached to a carboxylic acid on C1 Typically contain and even number of carbon atoms – between 10 and 20 Dodecanoic Acid Lauric Acid

9. Fatty Acids They are: Aliphatic molecules – they are both hydrophobic and hydrophilic But…overall they are hydrophobic Hydrophobic Hydrophilic Cell Membrane

10. Fatty Acids to know… Lauric Acid (C12) Myristic Acid (C14) Palmitic Acid (C16) Stearic Acid (C18) Laura, My Palm Stinks!

11. Types of Fatty Acids Saturated Fatty Acids: Only single bonds between the carbon atoms • Monounsaturated Fatty Acids: • Have one double bond in the carbon chain • Polyunsaturated Fatty Acids: • Have two or more double bonds

12. Unsaturated Fatty Acids trans double bonds cis double bonds

13. Shapes of Unsaturated Fatty Acids

14. Fatty Acids:Physical Properties Saturated and trans Fatty Acids: High melting points (solids) Perfect alignment – high Van de Waals intermolecular attractions • Trans fatty acids do not naturally exist – they are a man made product and are the most stable fatty acids

15. Fatty Acids:Physical Properties • Unsaturated cis Fatty Acids: • Lower melting point (liquid at room temp) • Do not have perfect alignment due to kinks in chain – low Van de Waals • Less stable – double bonds can break

16. Both are: C18H36O2 Saturated MP of 69° Unsaturated MP of 13°

17. Prostaglandins • They are: • Small polyunsaturated Fatty Acids that act like hormones mediating a range of symptoms from inflammation to blood pressure • Synthesized from Arachidonic Acid (AA)

18. Prostaglandins Most have a hydroxyl group on C11 and C15 and a trans double bond at C13 • PGE - those with a ketone on C9 • PGF - those with a hydroxyl group on C9

19. Inflammation is a… • Natural response to infection and injury • Disease like rheumatoid arthritis (inflammation of the joints)

20. Why do we care?

21. Non Steroidal Anti-Inflammatory Drugs(NSAIDs) • Drug class that includes: • Aspirin • Ibuprofen • Naproxen (Alveve) • Ketoprofen (actron) • Nabumetone (Relafen) Long term use can result in liver, kidney and gastrointestinal damage

22. NSAID effect and side effectStomach side effect Video Links

23. Homework Chapter 15.2 Pg 503 #15.6 – 15.18 (even)

24. SWBAT: Write structural formula of wax, fat or oil ID the reaction of a fatty acid and an alcohol or glycerol Chapter 15Waxes, Fats and Oils

25. Waxes Found in many plants and animals (leaves, stems, skin, fur and feathers) Is an ester of a saturated Fatty Acid and a long-chain alcohol (14-30 carbon atoms)

26. Fats and Oils: Triacylglycerols • The body stores Fatty Acids as fats and oils • Also called tryglycerides • Produced by esterification of glycerol and Fatty Acid groups

27. Fats and Oils: Triacylglycerols Most fats and oils are mixed triacylglycerolds with two or three different Fatty Acids from stearic acid from palmitic acid from myristic acid can be saturated or unsaturated

28. Writing Structures for Triacylglycerol • Each Fatty Acid is attached by an ester bond to one of the hydroxyl groups in glycerol • Alcohol Part: • In triglycerides always glycerol • Carboxylic Acid Part: • Three Fatty Acids

29. Fats and Oils:Physical Properties A fat is a solid at room temperature (fats in meat, butter, cheese) There are exceptions Typically from an animal source • Oil is usually liquid at room temperature (oils – olive, peanut, sunflower) • Typically from a plant source

30. Fats and Oils:Physical Properties • Saturated Fatty Acids have higher melting points because they pack together tightly • Animal fats usually contain more saturated Fatty Acids than vegetable oils

31. Melting Points

32. Homework Chapter 15.3 Pg 507-508 #15.20 – 15.28 (even)

33. SWBAT: Draw the structure of the product from a reaction of triacylglycerol with hydrogen, or an acid or base Chapter 15Chem Props of Triacylglycerols

34. Hydrogenation Hydrogenation of unsaturated fats converts carbon-carbon double bonds to single bonds Hydrogen gas is heated through oil with a nickel catalyst H2 • Partial hydrogenation changes oil to a soft, semisolid fat (crisco)

35. Why? • Chemical process patented in the 1940’s • used to convert oil surpluses from soybean farming • into spreadable fats (margarines) to alleviate butter shortage

36. Problem… • Incomplete hydrogenation leads to the formation of trans-double bonds→ Trans Fats trans fats in our food Video Link Trans Fats raise LDL (bad cholesterol ) levels in the body Consumption of Trans Fatsis correlated with a rise in CAD during 1960-2000 FDA prohibits use of Trans Fats & requires labeling

37. Hydrolysis • Breaking the ester bond – yielding fatty acid & glycerol • First step in the digesting of triglycerides in the body • Carried out by the enzyme lipase • Glycerol is soluble in water • Fatty Acids are not H+ lipase

38. Saponification (sapon = soap) Reacting triglycerides with a strong base Yields glycerol and Fatty Acid Salts (soap) Glycerol tritearate + 3 NaOH glycerol + 3 sodium stearate

39. What is Soap • Soaps are aliphaic molecules that have a polar part (facing water molecules) and a non-polar part (facing greasy dirt) • Ancient soap making – Animal fats are heated with a strong base (lye from burnt limestone) • Fatty acid salts – Sodium paltmitate: Na+ -OOC-(CH2)14-CH3 • Soap Making Video

40. Food Labels

41. Food Labels

42. Olestra • Fatty Acids from cottonseed or soybean oils • Composed of 6 to 8 long-chain Fatty Acids attached to sucrose rather than glycerol • We can’t digest it so “Fake Fat” goes straight through our system • GI problems occurred 

43. Homework Chapter 15.4 Pg 512-513 #15.30 – 15.36 (even)

44. SWBAT: Describe the characteristics of glycerophospholipids Chapter 1515.5 Glycerophospholipids

45. What are Glycerophospholipids? Similar to triglycerides except one hydroxyl group is replaced by the ester of phosphoric acid and an amino alcohol Glycerophospholipids Triglycerides • Bonded through a phosphodiester bond

46. Amino Alcohols Three amino alcohols found in glycerophospholipids are: serine ethanolamine choline

47. Lecithins Lecithins contain choline Fatty Acids can be same, different, saturated, unsaturated or mixture • Abundant in: • brain tissue • nerve tissue • egg yolks • wheat germ • yeast

48. Cephalins Cephalins contain ethanolamine and sometimes serine • Abundant in: • brain tissue • nerve tissue • egg yolks • wheat germ • yeast

49. Polar? Contain both polar and nonpolar regions Ionized alcohol and phosphate portion is called “the head” Can hydrogen bond with water Two Fatty Acids represent “the tail” • Hydrophobic Tails • Hydrophilic Head Group

50. Polar and Nonpolar Regions Most abundant in lipids in cell membrane Polar Head Nonpolar Tails